#include <pthread.h>
#include <stdio.h>
#include <unistd.h>

void *fun_1(void *);
void *fun_2(void *);

int main(int argc, char *argv[]) {
  pthread_t tid_1, tid_2;
  
  int ret;
  pthread_create(&tid_1,NULL,fun_1,(void*)0);
  pthread_create(&tid_2,NULL,fun_2,(void*)0);

  pthread_exit(0);
}

void *fun_1(void *num) {
  while (1) {
    printf("hello\n");
    sleep(1);
  }
}
void *fun_2(void *num) {
  while (1) {
    printf("world\n");
    sleep(2);
  }
}
